Synchronized machine gun for airplanes



Dec. 11, 1928.

o. A. Ross SYNCHRONIZEI'D MACHINE GUN FOR AIRPLANES Filed April 1927 INVENTOR Patented Dec. 11, 1928.

UNITED STATES.

oscan A. noss, or'nnw roan, 1v. Y.

P ATE-NTfOF F SYNOHRONIZED maonmn our: son nrn rmnns. 7

Application filed April 8, 1927. Serial No. 182,340

At the time the patent application for the.

aforesaid patent was filed, namely September 14, 1918, air planes of the pursuit type were employing propellers constructed of laminated wood, and the rotative speed of such propellers was limited to 100'0to 1600 R. P. M.,

it also being customary to employ gearing be-' tween the engine and propeller to obtain the maximum output of said engine.

At the present time metal propeller blades are employed at normal speeds 0t approximately 2000 R. P. M., and this speed may increase as much as 3000 R. P. M. in nosedive tive speeds of propellers, and after atrigger attacks with engine wide open. Obviously at these higher rotative speeds the increment of time betweenblade movements is very small, and whereas the rapidity of machine gun cycle has been increased from a;

normal of 400 to 800 shots and a maximum of 1200 per minute, the time interval between the pulling of the trigger, 'and'the passing of the bullet through the plane of movement-of the propeller blades has not increased in the same proportion as the rapidity of fire.

Asa matter of 'fact, at the present high rotais pulled as many as 3 blades, (one and onehalf revolutions). may pass a gun barrel before the bullet passes the 'planeof movement of the propeller. It is therefore obvious that, if a gun is timedfto fire just after a blade has passed at slow speed, after a pred.e-

termined increase in speed, the blades of the propeller will intercept said bullets, thereby causing injury to said blades.

One of the prime objects of this invention is to furnish means to automatically vary the time of firing of machine guns, whereby the bullets will pass between the blades, irrespec tive of the speed at which the propeller may be revolving.

Another object is tofurnish means where-.

by a plurality of guns may be fired sequentially at low propeller speeds and at such speeds as will permit sequential firing of two or more guns between successiveblade movements.

Another object is to furnish gun actuating means controlled by a speed governor, wherebe substantially uniform, this manner pered to be fired by and the novel features of the invention will be:

mittin the'governor to vary the actuating ing drawings, and particularly pointed tout.

in that portion of this instrument wherein patentable novelty is claimed .for certain and peculiar features ofthe system, it being understood that, within the scope"ofgfwhat' hereinafter thus is claimed, diversjfchangejsflin thegfonn, proportions, size and-minor, details l' of the structure may be made without departing from the spirit of, or sacrificing anyof the details of the invention.

In describing' the inventionj'in detail,

erence is had to'the accompanyingdrawings, wherein I. have illustrated embodiments of my invention, and, whereinllike'chara'cters of reference, designate corresponding parts throughout the several views, and, in

whichz- -Fig. 1, is a diagrammatic view ofan air plane'motor, four machine guns andfcon trol apparatus therefore, and is taken in art,

on line A-A of Fig. 2, and, Fig. 2, is a die-1 1.

grammatic View of. the governor controlledw contacting mechanism, and-is taken-0.11,- line B-B o f Fig. 1 and, Fig. 3, is a chart of the contact drum periphery shown in Figs. .1, and

2, and, Fig. 4, is a diagrammatic view of propeller, taken on line E'-E ofFig. 1, and,

relative location and operation of guns and Fig. 5 isa similar view, and Fig. 6 i519. diagrammatic view of a mechanical control appa ratus' for firingthe guns, and is takenon line C'-C of 'Fig. 7 and Fig. 7 is'also; a diagram- Referring toFigs. 1-, 2, and-3, to motor 1, having a two-blade propeller 2,-are suitably mountedmachine guns, R, S, T and U, adaptand U Preferably secured to half time shaft. 15 of motor 1, is governor 6,. secured by pin 7, the controlling disk 8; of which is secured to contact drum 9, slidably; mounted on shaft 15,

imbedded in the periphery ofwhich is contact strip 10 adapted to .COBtfiCflWlth brushes R,

' matic view of the same apparatus, and is 3 it taken on line D D ofFig. 6.

ele'ct'rmmagnets R, S, T

receiving energy through conductor'll, conby the energyrequired for said actuation will ZR; S, S; T", T; and- U, U; said strip 7 'nected to commutator 12, contacting with brush 13 communicating to the manually operated trigger 31.

- Referring to Figs. 6, and 7, machine ns R, S, T and U have triggers R, S, '1 and U adapted to be actuated by'cams R", S T and U, secured to drum 18, one end of which is mounted on bearing 19 adapted to rest-rain axial movement thereof a nd the other guided by screw member 20, Slidable on shaft 15 and actuated by governor 6.-

The operationof the system is as follow Referring to Figs. 1, 2, 3, 4, and 5, when motor 1 is at rest, the governor 6, assumes the .dotted position shown, the drum 9 impinges on collar 21, and the brushes R, R to U,

U, inclusive, are bearing along line X-X on said drum as shown in Fig. 3. 'If the motor 1 is now slowly rotated, the location of contact strip 10 is such, that, just after blade 2 haspassed gun- R and the manually operated trigger 31 is depressed, said gun willbe fired by the energizing of the following circuit.

R gun circuit, from positive energy to ,manually operated trigger 31, brush 12, commutator 13, conductor 11, contact strip10, brush R, wires R and R to the trigger operating magnet R returning to negative energy. As magnet R is actuated, it closes contacts R and R, establishing a partial circuit to gun S, as follows: from positive energy as before named to contact'strip 10, thence (assuming brush R is in contact wit said strip) to brush R wire R, contacts R and R wires'R and S to magnet S returning to negative energy. If drum 9 is.

stationary with brushes R and R in contact with strip 10, guns R and S will continue to fire in sequential order, gun R causinggun S to bafired by the operation of the mechanism which fires gunR. If the motor 1 is now accelerated to a speed whereby the time interval between blade movement is-insufiicient to safely fire gun S in sequential order b un R, the drum 9 will be revolving at a su clent speed, whereby contact strip 10will leave brush R before the contacts R? and R gun S, as contacts-R" and again causes firing of gun R,

Assume now themotor 1 has accelerated to a speed'of 3000 R. P. M., due to a nose dive attack. The governor 6, and drum 9 will assume the location shown by Figs. 1 and 2, and the firing of the guns as R, S, T and U will or 1/67 second per blade are closed, in this manner preventing the operation of .R are closed, p ,7 As drum 9 is slowly-rotated in the direction of the arrow Y, contact strip 1.0 will con-1 tact with brush S, will be established this sequential. order of firing being fully des rib d i P t out No. 1,454,137. e

be advanced substantially three-blade movements, as will be more fully hereinafter described. For the purpose of expeditious description, the following factors will be assumed:

Normal engine speed approximately 2000 R. P. M. or 4000 blade movements perminute, movement, or 67 per second.

Maximum engine speed approximately 3000 R. P. M. or 6.000 blade movement per minute, or 100 per second, or 1/100 second per blade movement.

Normal gun fire approximately 1000 shots per minute, or 1 6 per second, or, 1/16 second per shot. Time interval ofgun cycle includmg pulling of trigger up to passing of bullet through plane' of movement of propeller blades, to equal 1/3 of gun cycle, or, 1/50 second.

For the purpose of clearer illustration, the time interval represented by the widthof the blade is assumed to be nil, the'blade being further assumed to be a radial line of nil dimensionI From the foregoing computations, it will be obvious that, if gun R is ordinarily fired just after the blade 2 (Fig. 5) passes the gun barrel, and the motor 1 is operating at a s 'eed of 2000 R. P. M., the blade 2* willal'so ave passed said barrel before the bullet has reached the plane of movement of the propeller blades. If the engine speed is reduced to approximately 1500 R. P. M., the blade 2 will intercept the bullet and injury to said blade may result.

If the motor 1 is operated at 30003. P. M.

and gun R is ordinarily fired just after blade not oulyblade 2", f-

2" has passed the gun barrel, but in addition blade 2 will again pass the barrel before the bullet has reached the plane j of movement of the propeller. It is also obvious that blade 2 has just cleared the line of bullet travel and that of speed will cause said blade 2 to intercept .the bullet, resulting in probable injury to said blade.

such interference of bullets and blades. is"

eliminated in the following manner:

When the motor 1 is at rest or is revolved i" very slowly, the guns R, S, T and U are fired as 2, has passed the gun 5; however, as the engine speed is".

just after the blade, R, of Fi increase the governor 6 moves drum 9 axially on shaft 15, and away from step. collar 21,

in this mannercausing contact stri 10 to 4 Rs;

make earlier contact with brushes as S, S; T, T U, U whereby the firing period of said gun isadvanced with respect to. the location of the ropeller blades; as a mat- 1 obvious that at certain ,mcreased speeds, as the motor -1 accelerates ter of fact it will from zero revolutions, the guns, aslt to 'U,

a slight reduction '7 'j With the applicants novel system'of I synchronized machineguns sequentially} Iao i I as ment of gun fire, with respect'to 'propellerij 4 I the included'anglebetween brushesiRv and l be replaced by eccentrics fbr" operating the gun triggers and suchan arrangement will "a predetermmedincre inclusive, have their triggers ulled when the blades are directly opposite their gun barrels. a r

In this improved system for firing synchronized machine guns sequentially, the timing of firing'o guns as R "to U inclusive at high rotative propeller speeds, as for example 3000 R. P. M. is such, that, the bullet passes the plane of movement slightly before the equa-distant line of the blade 0 ening passes the line of the n barrel, see ig. 4, the included angle representing the factor of safety prior to intersection of the plane of movement of propeller blades, and the ineluded angle L, thefactor of safety, subsequent to said intersection, the latter angle be ing somewhat largerto compensate for variable ammunition characteristics. Referring to Figs, 6 and 7 at nil speed of motor 1, the governor 6 restrains screw to enter drum 18, thereby causing said drum to be rotated counter clockwise, (see'Fig. 7) and-the guns R to U inclusive will be'sequentiallyi fired just after a blade, as 2% or 2", has passed a gun barrel. As the speed ofmotorz 1 increases the governor 6 will restrain, screw" 20 to withdraw from thedrum, in this manner causing a clockwise 'movement of the drum, whereby the period ofsequential firing will be advanced with respect to the propeller line 'of action and the ultimate result of'g'un action will be the same as described in con-1 nection with Figs. 1, 2, 3, 4, and 5.

It is tobe noted that thecams as R" to U inclusive,fl have uniformly increasing .contours. Alsothat-the pressure of one trigger as R3, is releasedjust'as another, Ti, begins to bedepressed,'-in this-manner producing a uniform counter-torque to beovercome by the torque exerted by governor 6 on screw 20, for controlof advancingland retarding .move-' ment of drum-'18.

Figure 3 indicates arsenal-'8 tastes;

movement from as 1. It

will'be also noted from Figsq-l'and 3,

-S isslightly'greater than' degreesyand that'this is also'trueof brushes S to T and to U; This increase is for thepurpose of ,7

, compensating for the circumferential diS'-. placement of the gun barrels, with respect to thepropeller movement, as shown in Figs.

.. v and 5. f T-.- .However," as the interval of blad openin is sxnallera's gun R is" sequentially. "fired att and for the same reason ca m E f shorter,

" If desired the cams R 1 to U" mesa at,

avoid the necessity of spring return of said blades of anair plane propellerfme'ans for driving the propeller, means controlled ,by.,,

firing means."

.- the guns are restrainedto'pass between said iupon operation of the firing means. I 1

I of mallo v -jchine 'guns synchronized to. fire between the blades of an airlane propeller', means. for driving the prope er, means actuated by the propeller driving means for firin the guns in Q synchronism with the propeller b ades, means ducing the counter-torque to-be over 4 the torque produced b th goyemora v T, T U, U; and contact drum 9, maybe.

substituted by eight eccentrically opera ted levers four of which are arranged to continuously operate the triggers of gunsfa R .T and U, replacing the magnets B and U and the other four arrange erate the triggers sequentially with; the first named four eccentrics, the governor 6, in, ad,- dition to advancing the eccentric motion, also acting, at a predetermined increasefofspeed, 7 I to ann'ul the efiect of the last named fo r eccentrics to 0 rate the triggers of guns as,-R,S,Tand =WhatI-claimis:--' i 1.- In combination with a plurality of ma"- chine guns synchronizedto fire between the the driving means for firing the guns, insequential order, a' centrifuge driven by the y propeller driving means, and means eon;

trolled by the centrifuge Ifor varyingfl the 9 imoment'of fire of the sequential firing means with respect to the blade location, whereby the bullets of the gun are restrainedto pass be tween the blades at the plane ofniov'em ent of the blades upon operation of the sequential 2. ln combination with a plurality ,of ma};

'chine guns'arrangedf to fire sequentially be? v;

tween the-blades of an air plane'propeller, 7 means for driving the propeller, means act'u- "ated by the driving means for-firin theguns' in sequential order, a centrifuge riven b'y the propeller driving means, and'means con-Q trolled by thecentri ug'e for varying the mug the blade location, whereby the bulletsfrom" blades at the plane of movement of the blad In eomb'nation with-a plurality actuated by each gun for firin another gun, l'and -means for 'annulling sa dlast named means-upon a predetermined increase of sped fthe propeller driving means.

"combinat'o {er g'unU, the included" angle between:' ..=1between the lattice of an airplane propeller,

I: brushesilt and R? is lessthan-90 degrees;

means for drivin the propeller, means actulated by, the pio'pe ler driving means for fir ng the guns, sequentially "and in synchromsm i with the propeller blades, means actuated by g-eachgunrfor firin another gun, and means ment of fire of the firing means with respect to n with a plurality area 1.

propeller and inefiective to so fire at another ernor arranged to be rotated by the propeller drivingmeans, and means controlled by the governor for rendering the firing means effective to fire the gun at one range of speed of rotation of the propeller and ineffective to so fire a't'lzinother range of speed thereof.

6. In combination with a plurality of machine guns synchronized to. fire between the blades of an air-plane propeller, of means for driving the propeller, means for firing the guns in sequential order, a governor arranged to be rotated by the propeller driving means, and means controlled by the governor for rendering the firing means effective to firethe guns sequentially at one range of speedof the range of speed thereof. 7. In combination with a plurality of machine guns synchronized to fire between the blades of an air-plane propeller, of means for driving the propeller, a governor rotated by the propeller driving means, means controlled by the governor for initially firing the guns,

means controlled by the initial firing means.

for secondarily firing the guns, and means also controlled by the governor for rendering the secondary firing means effective to fire the guns at one-range of s eedof the propeller and inefiective to so re the guns durmg'anot-her range of speed thereo 8. In combination to a machine gun synchronized to fire between the blades of an air-plane propeller, of means for driving the propeller, a governor rotated by the propeller driving means, an electro-magnet arranged to fire the gun when energized, an electric circuit for sup lymg ener thereto, means controlled by t e governor or supplying energy to the circuit at fixed intervals and simultaneously varying the cycle of intervals in proportion to the speed of the propeller whereby the projectiles or the guns will be restrained to pass between the blades of the propeller.

9. .In combination with a. plurality oimachine guns synchronized to fire between the blades of an airplane propeller, of means for driving the propeller, agovernorrotated by the propeller driving means, an electro-mag net for each gun arranged to fire the amblades of an air-plane propeller, of meansfor driving the propeller, means controlled by the driving means for initially firing each gun in synchronism with the propeller blades, and means controlled by the initial firing means for firing another gun whereby a plu-- rality of guns will be fired in sequential order.

11. In combination with a machine gun synchronized to fire between the blades of an air-plane propeller, of means for driving the propeller, means for firing the gun, means controlled by the propeller driving means for rendering. the firing means effective to fire the gun at one range of speed thereof and ineffective to so fire at another range of speed.

Signed at New York city, in the county of New York, and State of New York.

OSCAR A. ROSS. 

